The invention belongs to the technical field of preparation methods of polypeptides and particularly relates to a preparation method of
liraglutide intermediate polypeptide GLP-1 (
glucagon-like
peptide-1) (7-37). The method comprises the following main steps: constructing recombinant
liraglutide engineering bacteria, expressing
liraglutide intermediate
fusion protein in a form of an inclusion bodyunder Echerichia coli induction, and performing denaturation, renaturation,
enzyme digestion, separation and purification to obtain the liraglutide intermediate polypeptide GLP-1 (7-37). Expression is changed into
intracellular insoluble inclusion body expression by changing recombinant
sequence signal peptides, and expression quantity is increased greatly; the washed inclusion body is subjectedto alkali
dissolution, a large quantity of denaturant is not needed, the inclusion body with
high concentration of
protein concentration being 20-30 g / L is added to an inclusion body
dissolution buffer, denaturation and renaturation time does not exceed 1 h, and
enzyme digestion can be performed after
dissolution; procedures are reduced, operation volume is reduced,
reagent cost is reduced, and industrialized enlargement is facilitated; UniSP-50XS cation exchange is adopted for separation and purification, and separation degree is high. The purity of the liraglutide intermediate polypeptide prepared with the method reaches 87% or higher, and the yield is higher than 85%.